Server side

keep a registry of activities so we can get the activity id and name from a central place

revisit activity enumeration, so we can do "find me activities of type $foo", or "get me some activities to fill up the mesh view"

revisit buddy enumeration, so we don't need the shared roster hack. it's possible that we should just find random people by finding random activities, and not worry about "get be some buddies to fill up the mesh view".